1078 THE BUTTEKFLIHS OF NEW ENGLAND. 



the Pieriiiae among Papilionidae. Some examples may be given, follow- 

 ing a systematic order. 



Ciilorippe celtis, one of the Apatiiridi, was reported in 1887, not only 

 to be swarming in great numbers in our southern states, but to be migrat- 

 ing, though I have been unable to obtain any definite statements regarding 

 their movements. 



Most of the cases, however, occur among the Vanessidi. Thus Mr. 

 B. P. Mann, while resident in Brazil, observed on Feb. 17 (early 

 autumn) great numbers of Coea acheronta following each other singly 

 at intervals across a meadow in front of his house, apparently migrating; 

 "the butterflies came with powerful, rapid, direct flight, perhaps from 

 three to five meters above the level of the meadow, from the direction of 

 a small hill near by.'" 



Another case within the tropics is I'ecorded of a ver}' different butter- 

 fly by Mr. Belt, which I give in his own words : — 



As we rode along, great numbers of a brown, tailed butterfly (Tlmetes cbirou) were 

 flying over to the southeast. They occurred as it were in columns. The air would be 

 comparatively clear of them for a few hundred yards, then we would pass through a 

 baud perhaps fifty yards in width, where hundreds were always in sight, and all trav- 

 elling one way. I took the direction several times with a pocket compass, and it was 

 always southeast. Amongst them were a few j'ellow butterflies, but these were not so 

 numerous as in former years. In some seasons these migratory swarms of butterflies 

 continue passing over to the southeast for three to five weeks, and must consist of 

 inillions upon millions of individuals comprising many difl'erent species and genera. 

 ... I know of no satisfactory explanation of these immense migrations. They occurred 

 every year whilst I was in Chontales, and always in the same direction. . . . The difll- 

 culty is there are uo retnrn swarms. (Nat. in Nicaragna, 152-3.) 



In Europe, the phenomenon has been observed in the allied Euvanessa 

 antiopa, whose irregularity of abundance is well known ; thus Swainson 

 says on Lewin's authority that in Great Britain "in March, 1790, a great 

 number were seen flying and soaring about for the space of twelve or four- 

 teen days : and then as if with one consent, they migrated from us and 

 were no more seen." The powers of flight of this insect ai-e referred to 

 above (p. 409). 



Fritsch of Prague states that a migration of butterflies , presumed to be 

 Aglais urticae, was seen atLaibach, which was about four hundred metres 

 broad and lasted for half an hour. And Cornelius says that a flight of 

 this same butterfly, lasting for half an hour, passed in a southeasterly 

 direction over the Lake of Neuchatel in July, 1828. 



We can return to our own country for the next instance, which is re- 

 lated by Behr of Eugonia californica and is the more interesting when 

 we recall the nocturnal flight of the allied E. j-album related above on p. 

 377. Dr. Behr says :— 



Tiif first migration I observed was on November 15th, 1856, when numbers of this 

 butterfly flew over San Francisco in a general direction of south-south-east. They 



